EVOH resins are excellent in transparency, antistatic property, oil resistance, solvent resistance, gas barrier property, fragrance retention and the like. The EVOH resins are melt-formable/moldable thermoplastic resins, and are used as packaging materials for food packaging or other various packaging applications.
It is conventionally known that an inorganic compound is added to such a EVOH resin for improvement of various properties of the EVOH resin. Studies are conducted on a method of properly dispersing the inorganic compound in the EVOH resin.
For example, PTL 1 proposes a method of preparing an EVOH resin composition containing inorganic particles dispersed therein by feeding a hydrous EVOH resin having a water content of not lower than 0.5 weight % into an extruder, adding an aqueous dispersion of the inorganic particles to the hydrous EVOH resin melted in the extruder, kneading the resulting mixture at a relatively low temperature, and drying the resulting hydrous resin composition.
PTL 2 proposes a method of preparing an EVOH resin composition containing an inorganic compound dispersed therein by kneading a mixture of an EVOH resin having a water content of not higher than 70 weight % and an aqueous dispersion of the inorganic compound at a relatively high temperature while removing water from the mixture to reduce the water content to not higher than 5 weight %.
PTL 3 proposes a method of preparing an EVOH resin composition containing clay mineral dispersed therein by melting an EVOH resin containing dry clay mineral in an extruder, feeding a small amount of water to the EVOH resin while kneading the EVOH resin at a relatively high temperature, and dispersing the clay mineral in the EVOH resin by utilizing a gasified water.
PTL 4 proposes a method of preparing an EVOH resin composition containing a water-swellable layered inorganic compound dispersed therein by melt-kneading an EVOH resin having a water content of 25 to 50 weight % with a dry water-swellable layered inorganic compound at a relatively low temperature, and drying the resulting hydrous resin composition in a drying apparatus.